This description refers to one or more embodiments of a method for manufacturing semiconductor devices and to a method for manufacturing a semiconductor device by using laser annealing.
Power semiconductor devices are tailored devices with optimised characteristics for specific purposes. For example, for improving the on-state characteristics of high voltage diodes and IGBTs (Insulated Gate Bipolar Transistor) it is desired to reduce the width or length of the drift region while maintaining the maximum reverse voltage. Therefore, a compromise between blocking capability, on-state losses, robustness and softness is desired. It is therefore an ongoing aim to tailor the doping profiles of the respective doping regions to meet the challenging demands, and suitable manufacturing processes needs to be developed therefor.
Attempts to reduce the width of the drift region while maintaining high reverse blocking voltage include the integration of a structured p-doped region in proximity to the backside of the device's substrate close to the n-emitter in case of a diode or close to the n-buffer in case of an IGBT. The integrated p-region generates a hole current when the electric field build up in reverse state reaches the backside of the device's substrate. The generation of the hole current can be caused by avalanche and provides additional charge carrier to prevent that the load current undergoes chopping during commutation of the device.